diff --git a/main.odin b/main.odin
index 4ddb8aa..fdab1d6 100644
--- a/main.odin
+++ b/main.odin
@@ -1237,15 +1237,26 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 
 	// ---- GSI query path ----
 	if idx_name, has_idx := index_name.?; has_idx {
-		_, gsi_found := dynamodb.find_gsi(&metadata, idx_name)
+		gsi, gsi_found := dynamodb.find_gsi(&metadata, idx_name)
 		if !gsi_found {
 			make_error_response(response, .ValidationException,
 				fmt.tprintf("The table does not have the specified index: %s", idx_name))
 			return
 		}
 
+		esk_gsi, esk_gsi_ok := dynamodb.parse_exclusive_start_key_gsi(
+			request.body, table_name, &metadata, gsi,
+		)
+		if !esk_gsi_ok {
+			make_error_response(response, .ValidationException, "Invalid ExclusiveStartKey")
+			return
+		}
+		defer {
+			if k, ok_gsi := esk_gsi.?; ok_gsi { delete(k) }
+		}
+
 		result, err := dynamodb.gsi_query(engine, table_name, idx_name,
-			pk_owned, exclusive_start_key, limit, sk_condition)
+			pk_owned, esk_gsi, limit, sk_condition)
 		if err != .None {
 			handle_storage_error(response, err)
 			return
@@ -1284,7 +1295,7 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 		}
 
 		write_items_response_with_pagination_ex(
-			response, final_items, result.last_evaluated_key, &metadata, scanned_count,
+			response, final_items, result.last_evaluated_key, &metadata, scanned_count, gsi,
 		)
 
 		if has_proj && len(projection) > 0 {
@@ -1420,14 +1431,25 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 
 	// ---- GSI scan path ----
 	if idx_name, has_idx := index_name.?; has_idx {
-		_, gsi_found := dynamodb.find_gsi(&metadata, idx_name)
+		gsi, gsi_found := dynamodb.find_gsi(&metadata, idx_name)
 		if !gsi_found {
 			make_error_response(response, .ValidationException,
 				fmt.tprintf("The table does not have the specified index: %s", idx_name))
 			return
 		}
 
-		result, err := dynamodb.gsi_scan(engine, table_name, idx_name, exclusive_start_key, limit)
+		esk_gsi, esk_gsi_ok := dynamodb.parse_exclusive_start_key_gsi(
+			request.body, table_name, &metadata, gsi,
+		)
+		if !esk_gsi_ok {
+			make_error_response(response, .ValidationException, "Invalid ExclusiveStartKey")
+			return
+		}
+		defer {
+			if k, ok_gsi := esk_gsi.?; ok_gsi { delete(k) }
+		}
+
+		result, err := dynamodb.gsi_scan(engine, table_name, idx_name, esk_gsi, limit)
 		if err != .None {
 			handle_storage_error(response, err)
 			return
@@ -1466,7 +1488,7 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 		}
 
 		write_items_response_with_pagination_ex(
-			response, final_items, result.last_evaluated_key, &metadata, scanned_count,
+			response, final_items, result.last_evaluated_key, &metadata, scanned_count, gsi,
 		)
 
 		if has_proj && len(projection) > 0 {
@@ -1579,13 +1601,13 @@ write_items_response_with_pagination_ex :: proc(
 	last_evaluated_key_binary: Maybe([]byte),
 	metadata: ^dynamodb.Table_Metadata,
 	scanned_count: int,
+	gsi: ^dynamodb.Global_Secondary_Index = nil,  // ← NEW parameter
 ) {
 	builder := strings.builder_make(context.allocator)
 	defer strings.builder_destroy(&builder)
 
 	strings.write_string(&builder, `{"Items":[`)
 
-	// Use serialize_item_to_builder directly an NOT serialize_item
 	for item, i in items {
 		if i > 0 do strings.write_string(&builder, ",")
 		dynamodb.serialize_item_to_builder(&builder, item)
@@ -1597,7 +1619,16 @@ write_items_response_with_pagination_ex :: proc(
 	fmt.sbprintf(&builder, "%d", scanned_count)
 
 	if binary_key, has_last := last_evaluated_key_binary.?; has_last {
-		lek_json, lek_ok := dynamodb.serialize_last_evaluated_key(binary_key, metadata)
+		lek_json: string
+		lek_ok: bool
+
+		// Use GSI serializer if we have a GSI, otherwise use base table serializer
+		if gsi != nil {
+			lek_json, lek_ok = dynamodb.serialize_last_evaluated_key_gsi(binary_key, metadata, gsi)
+		} else {
+			lek_json, lek_ok = dynamodb.serialize_last_evaluated_key(binary_key, metadata)
+		}
+
 		if lek_ok {
 			strings.write_string(&builder, `,"LastEvaluatedKey":`)
 			strings.write_string(&builder, lek_json)
@@ -1606,7 +1637,6 @@ write_items_response_with_pagination_ex :: proc(
 
 	strings.write_string(&builder, "}")
 
-	// We have to Clone the string before passing to response_set_body
 	resp_body := strings.clone(strings.to_string(builder))
 	response_set_body(response, transmute([]byte)resp_body)
 }